Eyeworld

EW REFRACTIVE SURGERY 74 by Maxine Lipner EyeWorld Senior Contributing Writer Equivalent results surface for PRK, LASEK, and epi-LASIK Visual outcomes and haze found to be alike P ractitioners want to give patients the best acuity possible. With surface abla- tion, does it matter wheth- er you opt for PRK, LASEK, or epi-LASIK for your patients? Not according to the results of a recent retrospective study involving 3,550 U.S. military personnel, said J. Richard Townley III, MD, corneal and refractive surgeon, Wilford Hall Ambulatory Surgery Center, Lackland Air Force Base, Texas. At the 2014 ASCRS•ASOA Sympo- sium & Congress in Boston, Dr. Townley reported on how the 3 surface ablation techniques compared in treating myopia. The concern with surface abla- tion has always been comfort, out- come, and haze, he noted. However, some high myopes do not qualify for LASIK, and for those with active vocations such as members of the military, concerns about fl ap dislo- cation can also come into play. As a result, surface ablation is common in this population. "Anywhere from 80% to 85% of our treatments are surface ablation," Dr. Townley said. Cognizant of the potential downsides, investigators wanted to compare the 3 techniques. "We wanted to make sure that we offered our patients the best surface ablation technique, given what's out there," he said. At Dr. Townley's center, in PRK the vast majority of patients have their epithelium removed with an Amoils brush. With LASEK, 20% alcohol is applied to the epithelium for 30 seconds before the epithelium is pulled back. Then the laser treat- ment is begun, and the epithelium is replaced, he said. With the epi- LASIK approach, an epithelial fl ap is fi rst created with an oscillating polymethacrylate blade, and after the laser application is complete the epithelial fl ap is laid back down, he explained. There are tradeoffs among the 3 procedures, Dr. Townley said. PRK with the Amoils brush has a cost difference from just using alcohol. But he views this technique as quick, easy, and reproducible. Meanwhile, with alcohol, it takes 30 seconds to apply and displace the epithelium. "While alcohol may be gentler if there's a leak from the alcohol well during application, it can be caustic to the conjunctiva or limbal stem cells," he said. "This could lead to more postop discomfort as well." So this demands a certain amount of fastidiousness from the practitioner. Epi-LASIK can also be more demand- ing. "Epi-LASIK takes a bit more time than just an Amoils brush and sometimes the epithelium can be quite adherent, leading some to use alcohol as well. But for this study, a polymer blade alone was used to create the epithelial fl ap. Surface study Included in the retrospective study were higher myopes, in the –3 to –6 D range, who underwent sur- face ablation at the center between 2002 and 2011, Dr. Townley said. Patients underwent either stan- dard PRK with epithelial removal, or "fl ap-on" LASEK or epi-LASIK. The majority of patients, 2,486, underwent standard PRK; another 616 underwent epi-LASIK, and the remaining 448 had LASEK. When investigators considered the out- comes at 1, 3, and 6 months, they found that they were virtually the same. "Ultimately there weren't any large differences among any of the techniques," Dr. Townley said. Both uncorrected and best corrected vi- sual acuity outcomes were basically equivalent regardless of which tech- nique was used, with all patients attaining good acuity. Also, investigators found that the haze rate was low, with virtually no distinction between PRK, LASEK, or epi-LASIK. "Individual outcomes and haze rates, everything from 3 to 6 months, were similar among the different techniques," Dr. Townley said. The total amount was just 0.1%. He attributes this low rate, in part, to the highly disciplined patient population that participated in the study. "Our patients generally are very good about taking orders and doing what we tell them to do," he said. "We have strict guidelines as far as ocular lubrication and sunglass use—even beyond 6 months after the surgery. We want them to wear sunglasses as much as possible to protect their eyes." In addition, a high dose of vitamin C was given to those who were not prone to kidney stones, and a longer steroid regimen was used for those that had treatments greater than 50 microns. However, no MMC was given. "There are a lot of centers that use MMC routinely with higher my- ope treatment," he said. "We don't use MMC except for enhancements and our haze rates are very low, but we compensate for this by using a longer steroid regimen." Dr. Townley puts his patients on fl uorometholone, using either a 2- or 4-month taper. Practitioner's preference The fact that all of the patients fared similarly puts the decision of which technique to choose squarely in the surgeon's hands. Dr. Townley said, "Surgeons can use their preference as to whether they leave the fl ap on or fl ap off, since there was no statistical difference in haze or fi nal visual outcomes with this population," he said. "Whatever works for their center should be safe and effective based on this study." That being said, patients may prefer one technique to another. "Anecdotally, patients sometimes complain of a little more discom- fort with the fl ap being left on," Dr. Townley said. "There is also the potential of the epithelial fl ap to slough in the early postoperative period, necessitating close follow-up and prolonged use of a bandage contact lens. Due to this concern and the potential discomfort, maybe it's best to discard the epithelial fl ap altogether." One limitation to the study is that while there are different tech- niques for removing the epithelium without laying this back down, these were all lumped together under PRK in the study, Dr. Townley noted. "There's no difference when we remove the fl ap or keep the fl ap on, but I'm curious now to look at which technique may be better to remove the epithelium," he said. "That's going to be the next comparison we will assess in more detail." EW Editors' note: Dr. Townley has no fi nancial interests related to his comments. Contact information Townley: james.townley@us.af.mil Alcohol well for LASEK September 2014 Amoils brush for PRK Source (all): J. Richard Townley III, MD

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